Compliant lower bearing with tapered outer diameter

ABSTRACT

A strut assembly includes a piston and a bearing housing around the piston. The bearing housing may also comprise a groove and a tapered surface opposite the groove. A bearing may be in the groove and proximate the piston. An outer cylinder may be around the bearing housing. The angle of the tapered surface may be based on a deflection angle between the outer cylinder and the piston. A wear plate may be around the tapered surface. An elastic material may be disposed between the tapered surface and the wear plate. The bearing housing may comprise a titanium alloy. The bearing housing may be configured to flex towards the wear plate.

FIELD OF INVENTION

The present disclosure relates to landing gear, and, more specifically,to a lower bearing for use in a strut assembly for landing gear.

BACKGROUND OF THE INVENTION

Aircraft landing gear may rely on strut assemblies to provide a smoothride over runways and support during loading. The strut assemblies mayinclude a bearing to smooth operation of the piston and housing. In someinstances, the landing gear may be at an angle relative to the groundwhile bearing the weight of the aircraft. Under load, the piston maydeflect relative to the outer cylinder and put increased pressure at anend of the bearing. The pressure increase can cause stick slip incantilevered shock struts. Stick slip may present a dangerous conditionunder which the aircraft may suddenly shift as the strut unsticks. Stickslip may be particularly dangerous when aircraft are being loaded orunloaded.

SUMMARY OF THE INVENTION

A bearing housing may comprise a cylindrical body and a groove formed inan inner surface of the cylindrical body. The groove may be configuredto interface with a bearing. A tapered surface may be formed on an outerdiameter of the cylindrical body.

In various embodiments, a wear plate may be disposed over the taperedsurface. An elastic material may be between the tapered surface and thewear plate. The tapered surface may be conical. A length of the taperedsurface may be less than half the length of the bearing housing. Thetapered surface may be tapered at an angle based on a deflection angleof the piston. A second tapered surface may be formed on the outerdiameter of the cylindrical body. An elastic material may be between thesecond tapered surface and the wear plate.

A strut assembly may comprise a piston and a bearing housing around thepiston. The bearing housing may also comprise a groove and a taperedsurface opposite the groove. A bearing may be in the groove andproximate the piston. An outer cylinder may be around the bearinghousing.

In various embodiments, an angle of the tapered surface may be based ona deflection angle between the outer cylinder and the piston. A wearplate may be around the tapered surface. An elastic material may bedisposed between the tapered surface and the wear plate. The bearinghousing may comprise a titanium alloy. The bearing housing may beconfigured to flex towards the wear plate. The bearing housing mayfurther include a second tapered surface opposite the groove.

The foregoing features and elements may be combined in variouscombinations without exclusivity, unless expressly indicated otherwise.These features and elements as well as the operation thereof will becomemore apparent in light of the following description and the accompanyingdrawings. It should be understood, however, the following descriptionand drawings are intended to be exemplary in nature and non-limiting.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter of the present disclosure is particularly pointed outand distinctly claimed in the concluding portion of the specification. Amore complete understanding of the present disclosure, however, may bestbe obtained by referring to the detailed description and claims whenconsidered in connection with the figures, wherein like numerals denotelike elements.

FIG. 1 illustrates an aircraft on the ground, in accordance with variousembodiments;

FIG. 2 illustrates a landing gear assembly, in accordance with variousembodiments;

FIG. 3 illustrates a partial cross sectional view of a strut assemblywith a tapered bearing housing, in accordance with various embodiments;and

FIG. 4 illustrates a partial cross sectional view of a strut assemblywith a tapered bearing housing, in accordance with various embodiments.

DETAILED DESCRIPTION

The detailed description of exemplary embodiments herein makes referenceto the accompanying drawings, which show exemplary embodiments by way ofillustration. While these exemplary embodiments are described insufficient detail to enable those skilled in the art to practice theinventions, it should be understood that other embodiments may berealized and that logical changes and adaptations in design andconstruction may be made in accordance with this invention and theteachings herein. Thus, the detailed description herein is presented forpurposes of illustration only and not of limitation. The scope of theinvention is defined by the appended claims. For example, the stepsrecited in any of the method or process descriptions may be executed inany order and are not necessarily limited to the order presented.

Furthermore, any reference to singular includes plural embodiments, andany reference to more than one component or step may include a singularembodiment or step. Also, any reference to attached, fixed, connected orthe like may include permanent, removable, temporary, partial, fulland/or any other possible attachment option. Additionally, any referenceto without contact (or similar phrases) may also include reduced contactor minimal contact. Surface shading lines may be used throughout thefigures to denote different parts but not necessarily to denote the sameor different materials.

As used herein, “aft” refers to the direction associated with the tail(e.g., the back end) of an aircraft, or generally, to the direction ofexhaust of the gas turbine. As used herein, “forward” refers to thedirection associated with the nose (e.g., the front end) of an aircraft,or generally, to the direction of flight or motion.

In various embodiments and with reference to FIG. 1, an aircraft 100 maycomprise a landing gear system including a first main landing gear110-1, a second main landing gear 110-2, and a nose landing gear 120.Nose landing gear 120 may be installed in a forward portion of theaircraft fuselage (e.g., forward of the engines) at the nose of thefuselage. First main landing gear 110-1 and second main landing gear110-2 may be installed aft of nose landing gear 120. First main landinggear 110-1, second main landing gear 110-2, and nose landing gear 120may generally support the aircraft when it is not flying, allowing theaircraft to take off, land, and taxi without damage.

In various embodiments and with reference to FIG. 2, nose landing gear150 may comprise a first wheel 156 and a second wheel 160 coupled tolanding gear strut 162. First wheel 156 may be operatively coupled to atire 154. In this regard, tire 154 may be mounted on first wheel 156.Tire 154 may define a pressurizable chamber between tire 154 and firstwheel 156. Similarly, a tire 158 may be mounted on and/or coupled tosecond wheel 160. First wheel 156 and second wheel 160 may operativelycouple to and/or rotatably couple to an axle assembly 152. Axle assembly152 may operatively couple to landing gear strut 162.

FIG. 3 illustrates a partial cross sectional view of a strut assembly200 with a tapered bearing housing, in accordance with variousembodiments. Strut assembly 200 may include piston 202 about axis 234projecting axially beyond an edge of outer cylinder 222 and end cap 220.Outer cylinder 222 may be made from metals such as steel, for example.Bearing 210 may slideably engage piston 202 on the radially innersurface of bearing 210. Bearing housing 212 may press against end cap220 in an axial direction between an end of bearing 210 and end cap 220.Scraper 218 is adjacent bearing 210 in an axial direction and scrapespiston 202 to prevent dust and debris from reaching between bearing 210and piston 202 as bearing 210 slides against piston 202. Hydraulic sealcarrier 204 may include dynamic seal 206 against piston 202. Piston 202may move in an axial direction relative to dynamic seal 206. Hydraulicseal carrier 204 may further include static seal 208 against outercylinder 222 and thus the static seal 208 may be restrained from motionrelative to outer cylinder 222.

In various embodiments, bearing housing 212 includes a cylindrical bodywith groove 228 on a radially inner surface and tapered surface 226opposite groove 228 along an outer diameter of the cylindrical body.Bearing housing 212 may be axially symmetric around axis 234. Bearing210 may be fitted into groove 228 of bearing housing 212. Taperedsurface 226 may be angled with respect to surface 224 that is adjacenttapered surface 226. Surface 224 may press against wear plate 216.Tapered surface 226 extends at least partially radially inward at pointsof tapered surface 226 axially further away from surface 224. Taperedsurface 226 may create a gap between tapered surface 226 and wear plate216 at the axial end of bearing housing 212. Thus, the gap between innersurface 230 of wear plate 216 and tapered surface 226 of bearing housing212 may be widest at an end of bearing housing 212.

In various embodiments not having wear plate 216, tapered surface 226may be angled with respect to outer cylinder 222. Tapered surface 226may be conical, convex, concave, stepped, or any other suitable shape toprovide a gap between wear plate 216 and tapered surface 226. The lengthof tapered surface 226 may be less than or equal to half the length ofbearing housing 212. In various embodiments, tapered surface 226 maycover the entire outer diameter of bearing housing 212. Tapered surface226 may have an angle with respect to wear plate 216 based on thedeflection of the strut relative to the outer cylinder in direction 232when strut assembly 200 is under load. Tapered surface 226 may be formedaround the outer diameter of bearing housing 212. Elastic material 214over tapered surface 226 may keep the gap between wear plate 216 andtapered surface 226 clean and free from debris. Bearing housing 212 andwear plate 216 may be made from a metal such as stainless steel and/or atitanium alloy, for example.

In various embodiments, tapered surface 226 tends to reduce stickingbetween bearing and piston under load by allowing for deflection ofpiston 202 relative to outer cylinder 222 without substantiallyincreasing pressure between bearing housing 212 and outer cylinder 222.Piston 202 may flex and deflect relative to outer cylinder 222, pressingbearing housing 212 towards wear plate 216. Tapered surface 226 maypress closer to wear plate 216, and elastic material 214 may compress aspiston 202 deflects relative to outer cylinder 222. Elastic material 214may compress between radially inner surface 230 of wear plate 216 andtapered surface 226 of bearing housing 212. Bearing housing 212 may flexto reduce the gap between wear plate 216 and tapered surface 226 asbearing housing 212 is pressed against outer cylinder 222 in response todeflection of piston 202. Wear plate 216 reduces burnishing of outercylinder as bearing housing 212 deflects under load. Bearing housing 212with tapered surface 226 may relieve pressure between piston 202 andbearing 210 as strut assembly 200 is loaded when compared to a flatbearing housing. Thus, bearing housing 212 tends to reduce wear and tearon strut assembly 200 by limiting point contact loads on the piston andreduce burnishing of the outer cylinder, for example.

FIG. 4 illustrates a partial cross sectional view of a strut assembly250 with a tapered bearing housing, in accordance with variousembodiments. Strut assembly 250 includes piston 252 with axis 272 andbearing 254. Piston 252 may be axially symmetric around axis 272.Bearing housing 256 may also be axially symmetric around axis 272.Bearing housing 256 may have wear plate 258 radially outward frombearing housing 256 and pressing against flat surface 266 of bearinghousing 256. Elastic material 260 may be between wear plate 258 andtapered surfaces 262 of bearing housing 256. Inner surface 264 of wearplate 258 may be opposite and radially outward from tapered surfaces 262of bearing housing 256. Tapered surfaces 262 may be conical,cylindrical, convex, concave, stepped, or any other suitable shape toprovide a gap between wear plate 258 and tapered surface 262. Bearinghousing 256 may have similar tapered surfaces 262 on both sides of flatsurface 266. Flat surface 266 of bearing housing 256 may press againstinner surface 264 of wear plate 258. In various embodiments not havingwear plate 258, flat surface 266 may press against outer cylinder 270.

In various embodiments, bearing housing 256 includes groove 268 on aninner diameter or radially inward facing side and tapered surface 262opposite groove 268 on an outer diameter or radially outward facing sideof bearing housing 256. Bearing housing 256 and wear plate 258 may bemade from a metal such as stainless steel and/or a titanium alloy, forexample. Tapered surface 262 is angled with respect to flat surface 266that presses against wear plate 258. Tapered surface 262 has an anglewith respect to wear plate 258 based on the deflection of piston 252relative to outer cylinder 270 in response to strut assembly 250 beingunder load. Elastic material 260 may be between inner surface 264 ofwear plate 258 and tapered surfaces 262 of bearing housing 256. Thedisposition of elastic material 260 over tapered surface 262 helps keepthe gap between wear plate 258 and tapered surface 262 clean and freefrom debris.

In various embodiments, tapered surface 262 may reduce sticking betweenbearing 254 and piston 252 under load by allowing for deflection ofpiston 252 relative to outer cylinder 270 with less pressure increaseagainst edges of bearing 254. Piston 252 may flex and deflect relativeto outer cylinder 270 and press bearing housing 256 towards wear plate258. Tapered surface 262 may be pushed closer to wear plate 258, andelastic material 260 may compress as piston 252 deflects relative toouter cylinder 270. Bearing housing 256 may flex to reduce the gapbetween wear plate 258 and tapered surface 262 as bearing housing 256 ispressed against the outer cylinder 270. Wear plate 258 may relievepressure between the outer cylinder 270 and bearing housing 256 whenstrut assembly 250 is loaded. Thus, wear plate 258 tends to reduce wearand tear on strut assembly 250 such as burnishing outer cylinder 270,for example.

Benefits, other advantages, and solutions to problems have beendescribed herein with regard to specific embodiments. Furthermore, theconnecting lines shown in the various figures contained herein areintended to represent exemplary functional relationships and/or physicalcouplings between the various elements. It should be noted that manyalternative or additional functional relationships or physicalconnections may be present in a practical system. However, the benefits,advantages, solutions to problems, and any elements that may cause anybenefit, advantage, or solution to occur or become more pronounced arenot to be construed as critical, required, or essential features orelements of the inventions. The scope of the inventions is accordinglyto be limited by nothing other than the appended claims, in whichreference to an element in the singular is not intended to mean “one andonly one” unless explicitly so stated, but rather “one or more.”Moreover, where a phrase similar to “at least one of A, B, or C” is usedin the claims, it is intended that the phrase be interpreted to meanthat A alone may be present in an embodiment, B alone may be present inan embodiment, C alone may be present in an embodiment, or that anycombination of the elements A, B and C may be present in a singleembodiment; for example, A and B, A and C, B and C, or A and B and C.

Systems, methods and apparatus are provided herein. In the detaileddescription herein, references to “various embodiments”, “oneembodiment”, “an embodiment”, “an example embodiment”, etc., indicatethat the embodiment described may include a particular feature,structure, or characteristic, but every embodiment may not necessarilyinclude the particular feature, structure, or characteristic. Moreover,such phrases are not necessarily referring to the same embodiment.Further, when a particular feature, structure, or characteristic isdescribed in connection with an embodiment, it is submitted that it iswithin the knowledge of one skilled in the art to affect such feature,structure, or characteristic in connection with other embodimentswhether or not explicitly described. After reading the description, itwill be apparent to one skilled in the relevant art(s) how to implementthe disclosure in alternative embodiments.

Furthermore, no element, component, or method step in the presentdisclosure is intended to be dedicated to the public regardless ofwhether the element, component, or method step is explicitly recited inthe claims. No claim element herein is to be construed under theprovisions of 35 U.S.C. 112(f), unless the element is expressly recitedusing the phrase “means for.” As used herein, the terms “comprises”,“comprising”, or any other variation thereof, are intended to cover anon-exclusive inclusion, such that a process, method, article, orapparatus that comprises a list of elements does not include only thoseelements but may include other elements not expressly listed or inherentto such process, method, article, or apparatus.

What is claimed is:
 1. A strut assembly, comprising: a piston; a bearinghousing around the piston and comprising a groove and a tapered surfaceopposite the groove; a bearing in the groove and proximate the piston;and an outer cylinder around and in contact with the bearing housing,the tapered surface creating a gap between the bearing housing and theouter cylinder.
 2. The strut assembly of claim 1, wherein an angle ofthe tapered surface is based on a deflection angle between the outercylinder and the piston.
 3. The strut assembly of claim 1, furtherincluding an elastic material between the tapered surface and the outercylinder.
 4. The strut assembly of claim 1, wherein the bearing housingfurther comprises a titanium alloy.
 5. The strut assembly of claim 1,wherein the bearing housing is configured to flex towards the outercylinder.
 6. The strut assembly of claim 1, wherein the bearing housingfurther includes a second tapered surface opposite the groove.
 7. Astrut assembly, comprising: a piston; a bearing housing around thepiston and comprising a groove and a tapered surface opposite thegroove; a bearing in the groove and proximate the piston; a wear platearound and in contact with the bearing housing, the tapered surfacecreating a gap between the bearing housing and the wear plate; and anouter cylinder around the wear plate.
 8. The strut assembly of claim 7,wherein an angle of the tapered surface is based on a deflection anglebetween the outer cylinder and the piston.
 9. The strut assembly ofclaim 7, further including an elastic material between the taperedsurface and the wear plate.
 10. The strut assembly of claim 7, whereinthe bearing housing further comprises a titanium alloy.
 11. The strutassembly of claim 7, wherein the bearing housing is configured to flextowards the wear plate.